1. Field of the Invention
The invention relates to machine tool systems, such as machining centers, mills, and lathes. More particularly, the field of the invention involves mechanisms for replacing the tool head in the spindle of a machine tool system.
2. Background Art
A typical computer numerically controlled (CNC) machine tool system includes a machining center having a tool changing mechanism. The mechanism removes a particular tool from the machining spindle and replaces it with a different tool. With machining centers of this type, a plurality of machining operations is conducted, which can require a like number of different tools be positioned on the spindle head. Thus, prior machining systems have included a plurality of tools available for on-demand usage.
In the development of modern machining centers, considerable focus has been placed on the tool changing mechanism, i.e., the device that extracts a particular tool from the rack and places it within the operating spinal at the machining location. For instance, the automatic tool changer of Hague et al., is depicted in U.S. Pat. No. 3,844,028, is exemplary of the automatic tool changing mechanisms.
The tools may be provided in. a variety of forms. Typically, the tools are mounted on a movable component that is integrated into the numeral control system of the machining center. The tools can be controlled to move a desired tool to a predetermined location to be extracted by the automatic tool changing mechanism. One type of tool storage and retrieval mechanism is shown in FIG. 1. In particular, magazine 10 includes a plurality of tool pockets 12 that are configured to firmly grasp a tool holder. Magazine 10 depicted in FIG. 1 is a turret type mechanism in which tool pockets 12 are interconnected by drive chain 14 or similar pocket positioning mechanism. Drive chain 14 is wound around hub 15 and is driven by a motor (not shown) under direction of the numeric control system or a manual system. In operation, drive chain 14 can be incrementally driven to position specific tool pocket 12 at the tool changing location. Magazine 10 also includes housing 17 that surrounds and supports tool pockets 12, drive chain 14 and hub 15. FIG. 2 presents magazine 10 as it is connected and arranged with milling center 11.
The present invention is a tool changer with a movable arm that removes and inserts of a tool from a stationary tool rack into the spindle of a machining center.
According to the present invention, the tool changer comprises a tool rack having a plurality of locations for holding tools, and an arm structured and arranged to be movable between the plurality of locations including a position which is capable of accessing a spindle of the machining center. Each of the locations further comprises a fork that has a plurality of prongs. The movable arm has two grippers, wherein one of the two grippers is disposed at an angle of about 90xc2x0 relative to the other of the two grippers.
The tool changer has rotational, vertical, and horizontal mechanisms for moving the movable arm from an arm-waiting position to a tool-gripping position. The rotational mechanism comprises a motor, a pulley associated with the motor, a belt which is attached to the motor and the pulley, and a gear wheel which is attached to the pulley. The gear of the rotational mechanism has a plurality of locations, and a sensor associated with the tool changer for sensing one of the locations on the gear, with each of the locations on the gear corresponding to one of the tools on the tool rack. The sensor associated with the tool changer is located at bottom of the tool changer.
The vertical mechanism for moving the movable arm vertically comprises a vertical shaft associated with the movable arm, and a cylinder connected to the movable arm. The cylinder is capable of moving the movable arm vertically upon the shaft. The horizontal mechanism for moving the movable arm laterally comprises a linear track associated with the movable arm, and a cylinder connected to the movable arm.
An advantage of the present invention is that the tool changer is more reliable than prior tool changers because of fewer parts in its assembly.
An advantage of the present invention is that the tool changer is lightweight and compact for handling and easily adapt to machining center with limited space.
Another advantage of the present invention is the faster time to change a tool in the spindle.
Another advantage of the present invention is that more tool racks may be easily added to the tool changer, therefore providing more tool storage and a larger variet changing capability.
Other advantages and benefits of the invention can be readily discerned from the following written description and accompanying figures.